To date, most of the clinical trials in systemic sclerosis (SSc) have been negative trials. One of the reasons for this may be that enrolled subjects are clinically heterogeneous and only a small subset of SSc patients respond to any one therapy. Better methods of classifying patients into clinically relevant subsets are needed. Multi-Analyte Profiling (MAP) is cutting edge ELISA-based technology that determines levels of serum biomarkers in an unbiased manner by simultaneously measuring hundreds of analytes using small serum sample volumes. Preliminary studies using MAP suggest that there are differences In levels of serum proteins among SSc patients with or without pulmonary arterial hypertension; however, studies have been limited by sample sizes consisting of patients enrolled at a single center. The establishment of a Proteomics and Clinical Core as part of the larger PSO grant will fund the establishment of a linked SSc serum repository and clinical database. Applying MAP technology to hundreds of serum samples will permit identification of a smaller subset of proteins that reliably predicts disease phenotype in a cost-effective manner. This serum protein signature will be validated and will then be used In subsequent clinical trials to ensure that patients with similar disease phenotype are enrolled. The Proteomics and Clinical Core will address three specific aims namely 1) to establish a state-of-the-art electronic SSc patient registry and biorepository that contains serum samples from SSc patients and appropriate controls along with relevant clinical information that is collected using standardized approaches, 2) apply Multi-Analyte Profile technology to 264 SSc and healthy control serum samples to discover and validate a small, core set of important SSc protein biomarkers. 3) work closely with the Bioinformatics Core to discover important associations between serum protein levels and clinical markers of SSc disease activity.